Overload device



y 1966 A. G. LINOWIECKI 3,262,581

OVEHLOAD DEVICE Filed May 11, 1964 5 Sheets-Sheet 1 FIG. I

INVENTOR.

ANTHONY G. LINOWIECKI ATTORNEYS July 26, 1966 A. G. LINOWIECKI 3,262,581

OVERLOAD DEVICE Filed May 11, 1964 5 Sheets-Sheet 2 INVENTOR.

40 ANTHONY G. LINOWIECKI ATTORNEYS July 26, 1966 A. e. LINOWIECKI 3, ,58

OVERLOAD DEVICE Filed May 11, 1904 5 Sheets-Sheet 5 INVENTOR.

4o ANTHONY G. LINOWIECKI ATTORNEYS United States Patent 3,262,581 OVERLOAD DEVICE Anthony G. Linowiecki, Michigan City, Ind., assignor to John H. Brickley, South Bend, Ind. Filed May 11, 1964, Ser. No. 366,370 8 Claims. (Cl. 212-132) The present invention relates to an overload device, and more particularly to an overload device responsive to the weight of an object which is being lifted by a hoist or the like. a

In the operation of hoists and the like, attempts are sometimes made to lift objects, the weight of which exceeds the maximumload limits of the hoist and/or its supporting structure, thus resulting in damage or destruction of the operating mechanism ofthe hoist or of the supporting structure, or both. load limiting devices have been used, but this type of device ha certain inherent difficulties which render it unsatisfactory for hoist application, particularly where the effective load on the hoist tends to momentarily fluctuate while it is being lifted and carried by the hoist. Further,

these prior devices could not effectively be calibrated or set to a specific maximum load at which the device would become effective to interrupt the operation of the hoist mechanism or control. It is therefore one of the principal objects of the present invention to provide a load limiting device for hoists and the like, which can be effectively calibrated to the desired maximum load, and which will operate reliably when a predetermined maximum load has been reached to interrupt the operation of the hoist.

Another object of the invention is to provide a load limiting mechanism for a hoist or similar mechanism, which will respond accurately to a predetermined load without responding to momentary load increases such as result from jerking, bouncing or swaying of the load on the hoist, thereby eliminating unintentional and harmless false excess loads on the mechanism, and which will readily reset itself for normal operation following overloading and interruption of the hoist mechanism.

Still another object of the invention is to provide a relatively simple and compact overload sensing and con trol device for hoists and similar load lifting mechanisms, which can be easily installed in any conventional or standard hoists or lift mechanism without any substantial changes in the mechanism or system being required, and which will operate with only slight movement in the device to operate a control switch, valve or the like, to render the hoist inoperative.

A further object is to provide a rugged, dependable load limiting device having a delayed action in response to excess loads to eliminate hunting and unnecessary shutdown of the hoist and including an adjustment means for changing the setting on the device to respond to various predetermined maximum loads.

Additional objects and advantages of the present load control device will become apparent from the following description and accompanying drawings, wherein:

FIGURE 1 is an elevational view 'of a hoist carried by a supporting structure and having the present load limiting device incorporated therein;

FIGURE 2 is a vertical cross sectional view of the present load limiting device illustrating the manner in which the device is incorporated in a conventional or standard hoist mechanism, and showing the operating mechanism of the device in the position assumed when the load is less than the maximum setting; and

FIGURE 3 is a vertical cross sectional view of the present load limiting device illustrating the manner in which the device is incorporated in a conventional or standard hoist mechanism, and showing the operating Simple spring control having a pin 38 extending through the housing 32 for I 3,262,581 Patented July 26, 1966 ice mechanism of the device responding to an excess load.

Referring more specifically to the drawings and to FIGURE 1 in particular, numeral 10 designates a conventional hoist having a reel, speed reducer and motor enclosed in the housing as shown, supported on a trolley 12, which is adapted to traverse the track 14 consisting of an overhead beam or boom. The present control mechanism 16 is connected to the housing or frame structure of the hoist by a stem 18 and to trolley 12 by a hook 20. The motor of the hoist is controlled by push button control 22 suspended on the end of a cable or tube 24, extending downwardly from control box 26 on the side of the housing. The hoist operates a chain 28 having a hook 30 on the lower end thereof for engaging the load to be lifted by the hoist. The trolley may be of any conventional type, the one shown consisting of housing 32 supported on the track by rollers 34 and 36, and

holding hook 20.

The present hoist overload control device is" secured to the housing or frame of hoist 10 by stem 18 threadedly received in hole 40 on the upper side of the housing. The stem is held rigidly in place by the seating of shoulder 42 on the upper surface of the housing around the hole. The overload device consists of a cylindrical housing 50 having an upper disc-shaped end wall 52 retained in the hollow interior of housing 50 by a split ring 54 seated in groove 56 in the internal Wall of housing 50. The upper end wall is sealed to the internal side wall of the housing by an O-ring gasket 58 seated in annular groove 60 in the external surface of the end wall. The hollow interior of housing 50 is closed at its lower end by a disc-shaped end wall 62 secured in the lower end of the housing by a split ring 64 seated in annular groove 66 in the internal wall of the housing. The lower end wall is sealed with respect to the internal surface of the housing by an O-ring gasket 68 seated in annular groove 70 in the end wall. The stem 18 is preferably formed integrally with the lower end wall. s I

Housing 50 and the two end walls 52 and 62 define a fluid-tight chamber containing a reciprocable piston 82 adapted to move from the position shown in FIGURE 2 to the position shown in FIGURE 3. The piston is sealed at the internal wall of the housing by an O-ring 84 seated in an annular groove 86 in the external wall of piston 82. A stem 88 formed integrally with piston 82 extends upwardly through upper end wall 52 and is connected to hook 20, the lower end of which is threadedly received in threaded opening 90 of stem 88.

The piston 82 separates chamber 80 into an upper and lowercompartment and contains two fluid passages 92 and 94, fluid passage 92 containing a restricted orifice 96 V in jet 98 at the lower end thereof, and urged to its seat on reduced diameter portion 102 by a spring 104 reacting between the head of the valve element and the upper side of jet 98[ Spring 104 determines the predetermined maximum load on the hoist by maintaining valve element 100 closed and hence the fluid above piston 82 until suflicient load has been placed on the hoi'st to cause the fluid acting on the upper side of the valve element to force it off its seat, thus permitting the fluid to flow to the underside of the piston and permitting the piston to shift to the upper end of the chamber. The check valve permits the fluid to flow readily from the upper compartment to the lower compartment as the piston moves upwardly relative to housing 50 under an excess load on the hoist, the orifice limiting the speed at which the piston can move from its lower position in FIGURE 2 to its upper position of FIGURE 3.

A check valve consisting of :a ball 106 seating on reduced diameter'portioh' 108' of passage 94 prevents fluid from flowing through the latter passage while the piston is moving upwardly, but permits the fluid to flow readily therethrough when the piston is returning to its original position, as shown in FIGURE 2. A coil spring 110 reacting between the upper surface of piston 82 and the intema-l surface of end wall 52 shifts the piston downwardly relative to housing to the position shown in FIGURE 2. The hydraulic fluid is placed in compartment after the end walls of the piston have been assembled in place, through passage 112 in end wall 52 closed by a plug 114 threadedly received in the upper end of passage 112.

The movement of the piston 'in response to an excess load on the hoist is transferred to a control switch mechanism contained in box 122 mounted on the side of housing 50, the switch having a lever 124 for closing contacts 126 and 128. The lever is actuated by a cam 130 mounted on reciprocable stem 132 for engaging roller 134 on the extension of lever 124. Stem 132 extends through the upper and lower walls of box 122 and is adapted to reciprocate in the holes in response to the relative movement between piston 82 and housing 50. The stem is urged upwardly by a coil spring reacting between the lower side of cam 130 and the bottom of box 122 to urge the stem into engagement with roller 134. The stem is held downwardly in its non-operating position by an arm or plate 142 extending laterally from stem 88 and secured thereto by set screw 144. The switch 120 is connected to the main control for the hoist motor by a cable 148. The switch and motor control are so arranged that when a maximum load is reached the hoist is rendered inoperative for further lifting, but not for lowering the load.

In the operation of the present overload control device mounted between the hoist and the trolley in the manner illustrated in the drawings, the piston is held in its lowermost position by spring 110 and the fluid in the upper portion of chamber 80'when the hoist is unloaded or is carrying a load less than the setting for the maximum load as determined by spring 104. In the event the hoist attempts to lift a load in excess of the setting on the overload control, piston 82 moves upwardly in opposition to the force of spring 110, causing fluid to flow past check valve 102 in passage 92 into the lower compartment of chamber 80. As the piston moves upwardly, arm 142 likewise moves upwardly, permitting stern 132 and cam 130 to move upwardly, the cam thereby engaging roller 134 and urging lever 124 to the right, closing contacts 126 and 128 to operate a relay and interrupt the operation of the hoist for lifting but not for lowering the load. As soon as the excess load has been removed from the hoist, spring 110 returns piston 82 to its original position, as shown in FIGURE 2, the fluid in the lower compartment of chamber 80 passing rapidly from the lower to the upper compartment through passage 94. As the piston returns to its lowermost position, arm 142 presses stem 132 downwardly, disengaging cam 130 from roller 134 and permitting lever 124 to move to the left and the two contacts 126 and 128 to move to open position. The degree'of load required to operate the overload control mechanism can be adjusted within limits by shifting cam 130 upwardly or downwardly on stem 132; however, the primary maximum load adjustment is accompl shed by varying the strength and/ or compression of sprmg 104. When valve 100 is closed, spring 110 has no appreciable effect on the response of the unit to excess loads, and when valve 100 is open, the movement of the piston relative to housing 50 is controlled primarily by the flow of fluid through orifice 96.

While only one embodiment of the present invention has been described in detail herein, various changes and modifications may be made to satisfy requirements.

I claim:

1. An overload device for hoists and the like, comprising a housing with a fluid chamber therein, means connected to said housing for supporting a load, upper and lower end walls in said housing, an axial hole in said upper end wall, a stem for connecting said lower end wall to a hoist, a piston in said chamber having two passages therethrough communicating with said chamher on opposite sides of said piston, valve means in One of said passages permitting the flow of fluid in only one direction, .a yieldable means urging said valve toward closed position wit-h a predetermined force, valve means in the other of said passages permitting the flow of fluid only in the opposite direction, a rod on said piston extending through the hole in the end wall, a spring means in said chamber urging said piston in the direction to move said rod into said chamber, a restriction in the passage through which the fluid flows as the piston moves in opposition to said spring means, a hoist control means having a lever, a reciprocating member adjacent to said lever, a cam on said member for engaging said lever when the hoist is in overloaded condition, and a means connected to said rod communicating with said member for holding said cam away from said lever when said hoist is in its no-overload condition.

2. An overload device for hoists and the like, comprising a housing with a fluid chamber therein, means connected to said housing for supporting a load, upper and lower end walls in said housing, an axial hole in said upper end wall, a stem for connecting said lower end wall to a hoist, a piston in said chamber having two passages therethrough communicating with said chamber on opposite sides of said piston, valve means in one of said passages permitting the flow of fluidin only one direction, a yieldable means urging said valve toward closed position with a predetermined force, valve means in the other of said passages permitting the flow of fluid only in the opposite direction, a rod on said piston extending through the hole in the end wall, a spring means in said chamber urging said piston in the direction to move said rod into said chamber, a restriction in the passage through which the fluid flows as the piston moves in opposition to said spring means, a hoist control means, and a means operatively connected to said rod and responsive to its movements so as to actuate said control means on overloading said hoist.

3. A load limiting mechanism for hoists and the like, comprising a housing with a cylindrical chamber therein, means connected to said housing for supporting a load, upper and lower end walls in said housing, one of said end walls having a stem projecting axially therefrom and the other of .said end walls having an axial hole therein, a piston in said chamber having two passages therethrough communicating with said chamber on opposite sides of said piston, valve means in one of said passages permitting the flow of fluid in only one direction, valve means in the other of said passages permitting the flow of fluid only in the opposite direction, a rod on said piston extending through the hole in the end wall, a spring means in said chamber urging said piston in the direction to move said rod into said chamber, a restriction in the passage through which the fluid flows as the piston moves in opposition to said spring means, a hoist control switch having a lever, a reciprocating member adjacent to said lever, a cam on said member for engaging said lever when the hoist is in overloaded condition, and a means connected to said rod communicating with said member for holding said cam away from said lever when said hoist is in its no-overload condition.

4. A load limiting mechanism for hoists and the like, comprising a housing with a cylindrical chamber therein, means connected to said housing for supporting a load, upper and lower end walls in said housing, one of said end walls having a stern projecting axially therefrom and the other of said end walls having an axial hole therein, a piston in said chamber having two passages therethrough communicating with said chamber on opposite sides of said piston, valve means in one of said passages permitting the flow of fluid in only one direction, valve means in the other of said passages permitting the flow of fluid only in the opposite direction, a rod on said piston extending through the hole in the end wall, a spring means in said chamber urging said piston in the direction to move said rod into said chamber, a restriction in the passage through which the fluid flows as the piston moves in opposition to said spring means, a hoist control means, and a means operatively connected to said rod and responsive to its movements so as to actuate said control means on overloading said hoist.

5. An overload device for hoists, comprising a housing with a cylindrical chamber therein, means connected to said housing for supporting a load, upper and lower end Walls in said housing, one of said end walls having a stem projecting axially therefrom and the other of said end walls having an axial hole therein, a piston in said chamber, two passages communicating with said chamber on opposite sides of said piston, valve means in one of said passages permitting the flow of fluid in only one direction, valve means in the other of said passages permitting the flow of fluid only in the opposite direction, a rod on said piston extending through the hole in the end wall, a spring means urging said piston in the direction to move said rod into said chamber, a restriction in the passage through which the fluid flows as the piston moves in opposition to said spring means, a hoist control means, and a means operatively connected to said rod and responsive to its movements so as to actuate said control means on overloading said hoist.

6. In a hoist overload device: a housing with a fluid chamber therein, means connected to said housing for supporting a load, upper and lower end walls in said housing, an axial hole in said upper end wall, a piston in said chamber, two passages communicating with said chamber on opposite sides of said piston, valve means in one of said passages permitting the flow of fluid in only one direction, valve means in the other of said chamber therein, means connected to said housing for supporting a load, end walls for said housing, one of said end walls having a stern projecting therefrom and the other of said end walls having a hole therein, a piston in said chamber, a passage means communicating with said chamber on opposite sides of said piston, .a pair of valve members in said passage, one of said valve members controlling the flow of fluid in one direction from one side of said piston to the other and the other of said valve members controlling the flow of fluid in the opposite direction, a rod on said piston extending through said hole in the end wall, a spring means urging said piston in the direction to move said rod into said chamber, a hoist control means, and a means operatively connected to said rod and responsive to its movements so as to actuate said control means on overloading said hoist.

8. In a hoist overload device: a housing with a fluid chamber therein, means connected to said housing for supporting a load, end walls for said housing, one of said end walls having a stem projecting therefrom and the other of said end walls having a hole therein, a piston in said chamber, a passage means communicating with said chamber on opposite sides of said piston, a pair of valve members in said passage means, one of said valve members controlling the flow of fluid in one direction from one side of said piston to the other and passages permitting the flow of fluid in the opposite direction, a rod on said piston extending through the holethe other of said valve members controlling the flow of fluid in the opposite direction, a rod on said piston extending through said hole in the end wall, and a spring means urging said piston in the direction to move said rod into said'chamber, and means actuated by movement of said rod relative to said housing for preventing overloading of the hoist.

References Cited by the Examiner UNITED STATES PATENTS 2,636,953 4/1953 Hunt 254-l74 X 2,790,340 4/1957 Cross 192150 X 2,823,915 2/1958 De Carbon 267-164 X 3,078,967 2/1963 Brown et al 267-64 X FOREIGN PATENTS 564,392 6/1957 Italy.

EVON C. BLUNK, Primary Examiner.

SAMUEL F. COLEMAN, Examiner.

A. L. LEVINE, Assistant Examiner. 

1.AN OVERLOAD DEVICE FOR HOISTS AND THE LIKE, COMPRISING A HOUSING WITH FLUID CHAMBER THEREIN, MEANS CONNECTED TO SAID HOUSING FOR SUPPORTING A LOAD, UPPER AND LOWER END WALLS IN SAID HOUSING, AN AXIAL HOLE IN SAID UPPER END WALL, A STEM FOR CONNECTING SAID LOWER END WALL TO A HOIST, A PISTON IN SAID CHAMBER HAVING TWO PASSAGES THERETHROUGH COMMUNICATING WITH SAID CHAMBER ON OPPOSITE SIDES OF SAID PISTON, VALVE MEANS IN ONE OF SAID PASSAGES PERMITTING THE FLOW OF FLUID IN ONLY ONE DIRECTION, A YIELDABLE MEANS URGING SAID VALVE TOWARD CLOSED POSITION WITH A PREDETERMINED FORCE, VALVE MEANS IN THE OTHER OF SAID PASSAGES PERMITTING THE FLOW OF FLUID ONLY IN THE OPPOSITE DIRECTION, A ROD ON SAID PISTON EXTENDING THROUGH THE HOLE IN THE END WALL, A SPRING MEANS IN SAID CHAMBER URGING SAID PISTON IN THE DIRECTION TO MOVE SAID ROD INTO SAID CHAMBER, A RESTRICTION IN THE PASSAGE THROUGH WHICH THE FLUID FLOWS AS THE PISTON MOVES IN OPPOSITION TO SAID SPRING MEANS, A HOIST CONTROL MEANS HAVING A LEVER, A RECIPROCATING MEMBER ADJACENT TO SAID LEVER, A CAM ON SAID MEMBER FOR ENGAGING SAID LEVER WHEN THE HOIST IS IN OVERLOADED 